As a result of my part time quest for comparative guage/satellite data I looked at

http://sealevel.colorado.edu/content/map-sea-level-trends which shows that the area East of the Philippines seems to be the main source of any rise in sealevel; and http://tidesandcurrents.noaa.gov/sltrends/sltrends.html which shows the majority of rise is in the 0-3mm range. The Areas showing falls in seal level show very large (-12mm) so it is hard to see where the global number of >3mm comes from.

From the first link.

Local trends are calculated with a least-squares fit of 10-day, 0.25 degree resolution grids of sea level. A trend, bias, annual, and semi-annual terms are fit simultaneously. Please note that these trends have been determined for a finite period (1993 - present), and reflect the impact of decadal scale climate variability on the regional distribution of sea level rise. Additionally, local sea surface height trends and variations are a result of many factors, including (but not limited to) local crustal displacement, glacial isostatic adjustment, steric effects, and even local wind patterns. Therefore you should consider these effects in interpreting local sea surface height time series derived from our gridded data sets.

The last sentence is perhaps being ignored by manny people - 20 years data local effects such as Philippines?

Martin A
Do you have a link for the datasets?

I like to look myself. I'm not a statistician, you can probably tell that, but it satisfies my natural scepticism that I'm not being conned or misled.

Lapogus
Thanks for the update, I'll be speaking to him tomorrow but I don't think he has bought anything from anywhere yet as he's still using what he bought last year, but I'll prompt him. We have a visit at Easter in outline planning seeing and smelling burning peat would be good.

Thanks for the links which I'll look at after I've made some raspberry jam using fruit from summer currently thawing. Long ago there was a company Adamsons in Blairgowrie producing the best raspberry jam I've ever tasted, I have to keep trying to match that childhood taste, frozen French raspberries probably won't do it but we'll see.

BTW Last time I looked on DMI Greenland was increasing ice mass at an above average rate this winter.

Martin A, SandyS

In 2010 a typhoon dumped 500 gigatons onto Eastern Australia, much of which filled a lake with no outflow except evaporation. This contributed to a transient 5mm drop in sea level. Any short term trends including 2010 will have little relevance to longer term trend analysis.

Internal variation in current sea level data is about +/-5mm.

If you want tide gauge data, there are several links here . The Colorado site is a useful gateway to a variety of sea level data.

Martin A

"3. There are indications that the trend change is an oscillation similar to several oscillations that occurred in the 20th Century"

Citation, please

Michael hart

Why do you think that sea level variation over the last 7000 years is a cyclic function?

Jan 9, 2015 at 9:59 PM | Unregistered CommenterEntropic man

I didn't say it was, EM.

It could be a simple sine curve, unlikely as that seems to me. But it doesn't have to be a simple sine curve to make the linear interpretation look foolish. You believe it should be a flat line? I don't even claim the Earth was in a steady state, never mind an equilibrium, before human emissions of CO2 started. You are the one who made a claim about a predicted sigmoidal curve in sea-level change rate-changes(!), yet you like enforcing linear interpretations on the data in the face of contradictory evidence when it suits you. So you have to justify your choice. (We are back to the null-hypothesis argument again.)

You cited a data interval of 18 years from 1993. You should thus be concerning yourself with shorter time periods than many thousands of years, such as, maybe, an association with the Atlantic oscillations.
Or maybe snowstorms in Antarctica which are claimed to significantly affect sea-level in the short term simply by virtue of the amount of solid water they dump some place where it is not able to melt and quickly return to the sea.

As a generalisation, I think you are still making the same 'hockey-stick' error of not realising that long term historical proxies are largely devoid of information about short term changes. Short term changes should be viewed with that in mind. This goes to the root of the problems of hockey-sticks, whether they are carved by Mann or Marcott.

Michael hart

I read your link. Their cycles are short term phenomena. In the context of long term tends they are noise. There is weak evidence for a small 60-year rate cycle in phase with a possible 60:year cycle in the modern temperature data. This is of too low an amplitude to impactt the longer term trend.

When interpreting trend data you look for the best fit.

For the 21 years since 1993 the best fit is linear, mainly because the error bars are too large to identify any acceleration or deceleration over that period.

Over the period since 1900, the acceleration is large enough to show above the noise. Whether it is part of a sigmoid or geometric trend, or a rising part of a cycle , is arguable.

In the millennial context of the Holocene, the pattern of sea level change is a good fit to temperature according to Marcott et al and the modern record. There is a sigmoid increase from 22000BP to 8000BP. The level peaks a metre or two above current levels for a while, then declines back towards current levels as the cooling trend begins. When temperature starts to rise again after 1880, so does sea level. The only cycle long enough to encompass this is the Milankovich interglacial, and AGW has interrupted the cooling phase one would have expected at this point.

Sorry, I think I just addressed both Ms as one person.

Entropic man
Eastern Australia - Queensland? What Lake and how much did its level rise or do you mean it turned Eastern Australia into a lake? 2010 which of these storms?

http://www.australiangeographic.com.au/topics/science-environment/2011/02/australias-worst-cyclones-timeline/

Martin A
A comprehensive lot of data.
Re links from Lapogus (whose red version got a mention on University Challenge the other night) on the John Daly link the sea level maps show the area east of the Philippines as having the largest negative anomaly; almost exactly the same area showing the greatest rise in satellite data. Coincidence or possibly ENSO related or something else?

Martin A
The items 2,3, and 4 in the summary from your link to Dean & Houston sums up my thoughts from way back in the discussion. Item 1 seems to answer my question about tide gauges. Item 3 confirms something Entropic man wasn't happy with when I pointed it out.

Summary
1. Satellite altimeter measurements are consistent with measurements by a large number of tide gauges
2. It is too soon to determine whether the increased trend measured from 1993 to 2011 is the leading edge of a permanent change in trend or an oscillation
3. There are indications that the trend change is an oscillation similar to several oscillations that occurred in the 20th Century
4. Additional years of satellite data are required to answer the oscillation question definitively

SandyS

Australia and 2010 sea level drop .

Regarding oscillations, the last 130 years of sea level data, if explained by a cycle, would need an oscillation with a 200-250 year period, for which I have seen no evidence.

Sandy

Rather than wading through EM's waffle, here is the link to the comparison of satellite to tide data - Move along - nothing to see here stuff..
And with regards to his Australian floods, the BoM doesn't seem to know about it
http://www.bom.gov.au/climate/enso/history/ln-2010-12/rainfall-flooding.shtml
It wasn't different to other extremes. They also only start at 1900 so avoid a lot of the data from the late 1800s that doesn't fit the narrative. Note it was just a La Nina - not as bad as the 74 one. The Murray Darling drains into the sea and not Lake Eyre so he can't have been talking about that. The map showed Eyre's catchment wasn't particularly wet.

It happened once , why not again?

ChrisM
I fear you're correct as Entropic man's linked article is paywalled and all the abstract says is

In 2011, a significant drop in global sea level occurred that was unprecedented in the altimeter era and concurrent with an exceptionally strong La Niña. This analysis examines multiple data sets in exploring the physical basis for the drop's exceptional intensity and persistence. Australia's hydrologic surface mass anomaly is shown to have been a dominant contributor to the 2011 global total, and associated precipitation anomalies were among the highest on record. The persistence of Australia's mass anomaly is attributed to the continent's unique surface hydrology, which includes expansive arheic and endorheic basins that impede runoff to ocean. Based on Australia's key role, attribution of sea level variability is addressed. The modulating influences of the Indian Ocean Dipole and Southern Annular Mode on La Niña teleconnections are found to be key drivers of anomalous precipitation in the continent's interior and the associated surface mass and sea level responses.

It is a satellite era record and notice that precipitation anomalies were among the highest on record.. not actually the highest. With all the storms in the timeline it would be something of a surprise if this was the only instance and there was nothing like in the tide gauge record. The abstract doesn't mention any correlation with Lake Eyre (which I was hoping EM would name or one of the other salt lakes) which is about 50ft below sea level and other Australian salt lakes. I can remember at least one occasion when Lake Eyre has been flooded to a level worthy of being mentioned in the BBC News. According to information in Wikipedia the events of 2009/10/11 seem unexceptional 2009 a once every 3 year event, 2010 and 2011 don't even get a depth mentioned as opposed to 2009 (1.5m); a 4 m (13 ft) flood every decade.

The Lake Eyre Yacht Club Records are interesting again no mention of a 2010 depth but there was a first since 1976 and a first time since 1990 event. So not unprecedented.

The Lake Eyre Yacht Club is a dedicated group of sailors who sail on the lake's floods, including recent trips in 1997, 2000, 2001, 2004, 2007 and 2009.[16] A number of 6 m (20 ft) trailer sailers sailed on Kati Thanda–Lake Eyre in 1975, 1976, and 1984 when the flood depth reached 3–6 m (10–20 ft). In July 2010 The Yacht Club held its first regatta since 1976 and its first on Lake Killamperpunna, a freshwater lake on Cooper Creek. The Cooper had reached Kati Thanda–Lake Eyre for the first time since 1990.

As the annual sea level rise during the 20th century was at a much lower rate than the 21st century then the 1975/76 events should be much more pronounced than 2010/11 in the data which doesn't appear to be the case. Nor do the Lake Eyre floods of 1999/2001 make much of an impression.

Entropic man's 500 gigaton(nes) is equivalent to two years Greenland ice melt and using his figure of 5.5mm of rise going into Australia then Greenland is contributing 2.5mm of sea level rise annually. If that is the case then the fact that this year Greenland is gaining ice mass well in excess of the 1990-2011 mean then that should show up in the sea level data. Greenland's exceptionally large 2011/12 summer melt may appear to be the recovery from the Australian event in the data.

Sandy

The link for the paper on tidal vrs satellite didn't come across. Here it is.
http://download.springer.com/static/pdf/628/art%253A10.1007%252Fs10712-011-9119-1.pdf?auth66=1420933438_7ff61fcbcce862c7624bb5e4accfc00f&ext=.pdf
With regards to the Australia causing the tides, EM was just grazing abstracts without reading the actual paper. It does seem to be form for him, like when confronted with actual data, he changes the subject.
Note how none of the authors of the paper he referenced were Australian nor do the BoM mention It . The Colorado scientists had problems explaining sea level drop so latched onto a La Nina in Oz. Though it doesn't cover the same period , the animation shows that wet areas are often matched by dry regions.
http://upload.wikimedia.org/wikipedia/commons/1/15/Global_Gravity_Anomaly_Animation_over_LAND.gif
There also seems to be no mention in the CRACE publications of the paper so they can't have seen it as important or relevant. Note that the 1974 La Nina in Oz (which was bigger than the 2010-11 one) didn't cause sea level to drop. That's GW for you - the land of irreproducible results.

It happened twice , why not three times?

EM
Stop being a troll. It was sea level rise and you started the discussion - remember.

HaroldW, ChrisM thanks for all the help and information.

Entropic man
For clarification are we talking about natural or anthroprogenic sealevel rise? I was under the impression that your discussion was focused the human element.

Don't worry about Entropic, Radical. He rather enjoys wallowing in his swamp of ecological nightmares.

SandyS

Yes, lacking evidence for sufficient natural forcing to produce the observed temperature change I default to anthropogenic warming.

I don't expect it to be linear either. Amplification from reduced albedo, CO2 and methane from permafrost decay, and methane from sediments and clathrates are all likely to accelerate the rate of temperature change and the consequent rate of sea level rise.